1. Field of the Invention
The present invention relates to a laser driving technology in an optical disc apparatus.
2. Description of the Related Art
In an optical disc apparatus an output of a laser is controlled according to a state of the apparatus. One such example is described in JP-A-4-6636. In a section titled “Means to Solve the Problems” in this official gazette, there is a description that “during a standby period when no recording or playback operation is performed, either the laser output is lowered or a high frequency superposition of the laser drive current is stopped.” JP-A-2000-251266 in its paragraph [0077] has a description that “in a disc recorded with a CLV or MCLV method, when a seek operation is performed toward the inner circumferential side from the present beam spot position, the laser power is reduced from that of the normal playback operation, preventing a possible destruction of data.”
Conventional optical disc apparatus do not take into consideration satisfactory measures against the problems that a laser beam radiated against an optical disc, even if its power level is for a playback, does degrade recorded marks on the optical disc and that the emission of the laser beam gradually deteriorates the laser itself. Nor do they adopt a satisfactory means to address the problem that lasing the laser generates unwanted radio waves from the optical disc apparatus and that avoiding the radio waves can impair the responsiveness of the optical disc apparatus.